Solderless connection in LED module

ABSTRACT

The electrodes of a light emitting diode (LED) is coupled to the terminals of a package with solderless pressure contacts. Each package is housed in a module with a bed on which the bottom electrode of the LED rests, and a pressure plate which is coupled to the top electrode of the LED. The pressure plate slides along four vertical posts to exert pressure to an LED package against a bed to form solderless pressure contacts. A plurality of LED packages can be lined up in a row to form a light strip, with the top pressure plate extended to form the bed of an adjacent module. A plurality of LED packages can also be arranged a matrix array display panel, where a plurality of lower terminals rests on one row of common bed of a number of parallel horizontal common beds, and where a plurality of upper terminals are pressed under a column of parallel vertical common pressure plates, so that any individual LED at the cross-point of a common bed and a common pressure can be randomly accessed.

This application is a continuation of application Ser. No. 10/436,748,filed May 14, 2003, now U.S. Pat. No. 6,911,731.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to light emitting diodes (LED), particularly to amodule for housing LED package.

2. Brief Description of Related Art

FIG. 1 shows a prior art for mounting LEDs, such as LED 11, on a displaypanel. The LED 11 is mounted on a substrate 10, which is lined withprinted circuits 101, 102. The top electrode of the LED 11 is wirebonded to circuit 101 with solder and the bottom electrode of LED 11 issoldered to the circuit 102. The drawback of such a LED panel is poorheat removal, degrading light illumination efficiency. Another drawbackis the complicated process of soldering the wire to the printed circuitand the maintenance thereof.

SUMMARY OF THE INVENTION

An object of this invention is to improve the heat removal of a lightemitting diode display panel. Another object of this invention is toeliminate soldering the LEDs to the panel, thereby avoiding thecomplicated process and maintenance.

These objects are achieved by using pressure contact to attach the LEDsto a package. Each LED is mounted in a package with solderless pressurecontacts between the LED electrodes and the terminals of the package.These packages are housed in a module with a flat bed and a pressureplate. When the top pressure plate is clamped, solderless pressurecontacts between the LED electrodes and the terminals are formed.

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

FIG. 1 shows a prior art LED display panel using soldering contacts.

FIG. 2A shows the top view of the basic structure of an LED packagebased on the present invention; and FIG. 2B shows the side view of theLED package shown in FIG. 2A.

FIG. 3A shows a second embodiment of the LED package; FIG. 3B shows athird embodiment of the LED package.

FIG. 4A shows a fourth embodiment of the LED package; FIG. 4B shows afifth embodiment of the LED package.

FIG. 5 shows a basic structure of a module for housing a LED packagebetween a pressure plate and a flat bed.

FIG. 6 shows a first version of a pressure plate pressing against an LEDpackage.

FIG. 7A shows a second version of a pressure plate pressing against anLED package; FIG. 7B shows a third version of a pressure plate pressingagainst an LED package anchored in a recess.

FIG. 8A shows fourth version of the pressure plate of the LED package;FIG. 8B shows a fifth version of the pressure plate.

FIG. 9 shows a multiple LED modules connected in series to form alighting strip.

FIG. 10 shows a matrix array of LED packages with lower terminals in thesame row resting on one common bed of multiple parallel rows of commonbeds, and with upper terminals of the LED packages pressed by one commonpressure plate of multiple parallel columns of common pressure plates.Each LED package can then be randomly accessed.

FIG. 11 shows an LED package with a spring inserted between the bottomelectrode and the lower terminal to increase pressure at the contacts.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 2A shows the top view of a light emitting diode package 20. The LEDhas a bottom electrode mounted by conductive glue 219 on the recess of ametal substrate 23 serving as a first terminal of the LED 21. Aninsulating washer 24 is placed over the substrate, as shown in thecross-sectional view FIG. 2B of the package 20. The top electrode of theLED 21 is connected by metal strip or wire 26 to the top of the metalplate 22. Over the washer 24 is a hollow metal plate 22 covering overthe end of the wire 26, serving as the second terminal of the of the LED21. The hollow upper terminal 22 allows the light emitted from the LED21 to transmit.

FIG. 3A shows a second version of the package 20 for an LED 21. Similarto FIG. 2B, the LED 21 is mounted on a substrate 232 serving as a lowerterminal, and the substrate 232 is insulated by a washer 24 from thehollow upper cover 222, serving as an upper terminal. However, the wire26 connected to the top electrode of the LED 21 terminates over theshoulder of the upper terminal 222.

FIG. 3B shows a third embodiment of the LED package 20. The structure isof the package 20 for LED 21 is similar to that in FIG. 3A withcorresponding substrate 232 and insulating washer 24. However, the holeof the hollow upper terminal 224 is smaller that the top surface of theLED so that the inner shoulder of the upper terminal 224 lies over therim of the LED 21, thus making contact to the top electrode of the LED21 without using a wire.

FIG. 4A shows a fourth embodiment of the LED package 20. The structureis similar to that shown in FIG. 3A with corresponding referencenumerals. The only difference is that the substrate or the lowerterminal 234 is recessed and the LED 21 is anchored in the recess 25.

FIG. 4B shows a fourth embodiment of the LED package 20. The structureis similar to that shown in FIG. 3B with corresponding referencenumerals. The only difference is that the substrate or lower terminal244 is recessed and the LED 21 is anchored in the recess 25.

FIG. 5 shows the basic structure of a module for housing a LED package.The module has a flat bed 29 on which the lower terminal 23 of an LEDpackage rests, and a top pressure plate 28, which has a window 272 forthe emitted light to transmit through the hole 27 of the upper terminal22 of the LED package 20. The bed 29 is inserted with four verticalexpandable telescopic posts 285 at its corners 291. The upper ends 281of the posts are attached to four corners of the top pressure plate 28so that the top pressure plate can slide along the vertical posts likean elevator.

FIG. 6 shows the LED package 20 in the module shown in FIG. 5 beingcompressed by the top pressure plate 28 when the top pressure plate 28is lowered. The bottom terminal 23 of the LED package 20 (of the typeshown in FIG. 2B for instance) is pressed against the bed 29 of themodule. The upper terminal 22 of the LED package 20 is compressed by thetop pressure plate 28 with the window 272 of the top pressure platealigned with the LED package 20, so that the emitted light from the LEDpackage 20 can pass.

FIG. 7A shows a second version of the top pressure plate 286 which has arecess. When this angled top pressure plate is lowered to compress anLED package 20, the pressure plate 286 caps over and anchors the LEDpackage 20. The LED package 20 shown is of the type shown in FIG. 2B forinstance. When the top pressure plate 286 is compressed, the lowerterminal 23 of the LED package makes intimate solderless contact withthe bottom metal bed 29, and the upper terminal 22 of the LED packagemakes intimate solderless contact with the top pressure plate 286.Between the pressure plate 286 and the bottom plate 29 is an air-gap.

FIG. 7B shows a third version of the LED module. The structure issimilar to that shown in FIG. 7 a with corresponding reference numeralsexcept the bottom metal bed 296, which has a recess 25 to anchor the LEDpackage 20.

FIG. 8A shows a second version of a top pressure plate 282 which is ofinsulating material. Otherwise, the structure is similar to that shownin FIG. 5 with corresponding reference numerals 281 for the ends of thevertical posts and 272 for the window. Since the top plate 282 is ofinsulating material, the bottom surface of the 282 top pressure plate iscoated with conducting material 284 to provide electrical contact forthe upper terminal of the LED package.

Similarly in FIG. 8B, the lower bed 292 can be of insulating materialsuch as a printed circuit board. In such a case, the top surface of thebed 292 is coated with a conducting layer 294 so that the lower terminalof the LED is in electrical contact with an external circuit.

FIG. 9 shows a second embodiment of the LED module for a light strip. Aplurality of LED modules are lined up in a row. The top plate of the 31is of Z-shape and is extended to become the bed of an adjacent module.In each module, the lower terminal 23 of an LED package 20 is pressed ona bed to make a solderless contact, and the upper terminal 22 is pressedto make solderless contact with the top pressure plate 31 by aligningthe window 37 with the LED package 20 and sliding the holes 381 of thetop plate 37 along the vertical posts 385 inserted in the holes 391 inthe beds. In so doing, the LED packages in the same row are connected inseries.

FIG. 10 shows a third embodiment of the LED module serving a displaypanel. An array of LED packages 20 are arranged in a matrix at the crosspoints along parallel horizontal beds 491, 492, etc. and parallelvertical top pressure bars 481, 482, etc. The bottom terminals 23 of theLED packages 20 rest on the horizontal beds, and the upper terminals 22of the LED packages 20 are pressed under the vertical top pressure bars.These top bars have windows 47 for light from the LED packages 20 topass. The pressure of the vertical top bars clamps the LED packages inposition and makes firm solderless electrical contacts between upperterminals 22 and the vertical bars 481, 482. By coincident addressing,individual LED packages can be accessed and energized.

FIG. 11 shows another embodiment of the LED module 20. The structure issimilar to that shown in FIG. 4B, with top electrode 22 of the LED, abottom electrode 23, a upper terminal 286, and a lower terminal 296 witha recess 25. A spring 255 is inserted between the bottom electrode ofthe LED and the recess 25. The spring 25 pushes the top electrode of LEDagainst the upper terminal 286 to make a solderless pressure contact,and also pushes against the bottom electrode 23 of the LED to makesolderless pressure contact. The insertion of the spring 255 increasesthe pressure at the contacts.

While the preferred embodiments of the invention have been described, itwill be apparent to those skilled in the art that various modificationscan be made to the embodiments without departing from the spirit of thepresent invention. Such modifications are all within the scope of thisinvention.

1. A module for light emitting diode (LED) packages to effect solderlesscontacts between LED electrodes and LED package terminals, comprising: alight emitting diode (LED) having a bottom electrode, and a topelectrode; an LED package for mounting said LED having a lower terminalon which said bottom electrode rests, and an upper terminal having aconnection to said top electrode and insulated from said lower terminal;a metal bed on which said lower terminal lies; and a pressure plate tosandwich said package over said metal bed to effect solderless pressureelectrical contacts, said pressure plate having a window for lighttransmission from said LED package, wherein said window is smaller thanthe top surface of said LED package so that the shoulder of the windowrests against said LED package.
 2. The module as described in claim 1,wherein said connection is a metal strip.
 3. The module as described inclaim 1, wherein said connection is a wire.
 4. The module as describedin claim 1, wherein said metal bed has a recess to anchor said LEDpackage.
 5. The module as described in claim 1, further comprising fourtelescopic posts to support said pressure plate over said metal bad,wherein said pressure plate slides along said posts to clamp said LEDpackage against said metal bed.
 6. The module as described in claim 1,wherein said pressure plate is an insulating material and is coated atthe bottom surface with conductive material.
 7. The module as describedin claim 1, further comprising more than one module arranged as a matrixarray display panel, wherein more than one said lower terminal of an LEDpackage are mounted along one common metal bed of a plurality ofparallel horizontal said metal bed, more than one said upper terminal ofan LED package are pressed under one common pressure plate of aplurality of parallel vertical pressure plates, and each said LED at thecross-point of said common metal bed and said common pressure plate canbe energized coincidentally from one of said parallel horizontal bedsand one of said parallel vertical pressure plates.
 8. The module asdescribed in claim 4, further comprising a spring inserted between saidbottom electrode and said recess.
 9. The module as described in claim 1,wherein said pressure plate is a metal plate.